Curcumin, chemically known as 1,7 bis (4-hydroxy-3-methoxy phenyl)-1,6 heptadiene-3,5-dione belongs to a curcuminoid class of the popular Indian spice Curcuma longa, a perennial herbaceous plant of Zingiberaceae (ginger) family, which is cultivated in India, China and other tropical countries. The rhizome is known for its pharmacological properties and has been used in food and Ayurvedic medicines since thousands of years for its medicinal properties. Curcumin is known for its use in inflammatory conditions, pain, liver disorders, and wide variety of pulmonary, gastrointestinal and skin diseases.
Curcuminoids are linear diarylheptanoids derived from turmeric and are natural phenols that impart yellow color to turmeric. Natural curcuminoids are poorly soluble in water. Hence, the curcuminoids are synthesized using chemical methods to increase the solubility and bioavailability.
Curcuminoids are traditionally used in the treatment of arthritis, gastrointestinal disorders, skin wounds, inflammation, cancers, cystic fibrosis, heart burn, Alzheimer's disease etc. Curcuminoid is an effective antioxidant with the ability to scavenge free radicals generated in the body as a result of various metabolic processes. Curcuminoids are also useful as food supplement.
Tetrahydrocurcuminoid is a colorless hydrogenated phenolic compound derived from curcuminoids and is known for its anti-oxidant activities, skin protection and inhibition of tyrosinase. The lack of yellow color and biological activities render the use of tetrahydrocurcuminoid in food and cosmetic applications. However, the poor systemic bioavailability due to poor solubility in water limits the use of the compound.
Solubility of tetrahydrocurcuminoid was determined in various vehicles such as oils, co-surfactants, surfactants etc. and also by using different polymers. Different methods are also employed to increase the solubility and hence, the bioavailability of tetrahydrocurcuminoid. Several conventional techniques based on physical parameters such as heat, pH, and complexations with metal ions, serum has been proposed to increase the solubility. Even though, curcumin exhibits more pharmacological properties, the amount of total curcuminoids absorbed is less.
The chemical and synthetic methods are also proposed to synthesize the white curcumin. However, these methods involve complicated steps with moderate purity of the final product. In addition, most of the proposed processes use the re-crystallization step, which increases the complexity of the process.
The PCT application numbered PCT/US2001/032441 titled “Process of making and method of use of tetrahydrocurcuminoids to regulate physiological and pathological events in the skin and mucosa cells” discloses a method for producing tetrahydrocurcuminoids by saturating two olefinic bonds in a mixture of curcuminoids. This process is carried out by mixing ethyl acetate and curcuminoids at room temperature. Further, catalytic hydrogen transfer reagent is added followed by palladium carbon with continuous stirring. The mixture is cooled and the resultant mixture is filtered and washed with toluene to obtain toluene extract. The toluene extract is further washed with hydrochloric acid and water. Finally, toluene is removed under vaccum to obtain a paste of tetrahydrocurcuminoids. The method involves continuous steps of washing and filtration, which may increase the cost of the process and also may reduce the purity of the final product.
The PCT application numbered PCT/US2000/008711 titled “Use of tetrahydrocurcuminoids to regulate physiological and pathological events in the skin and mucosa” discloses a method for producing tetrahydrocurcuminoids by saturating two olefinic bonds in a mixture of curcuminoids. The method involves the steps of mixing ethyl acetate and curcuminoids at room temperature. The hydrogen transfer reagent is added, followed by palladium carbon as catalyst with continuous stirring. The mixture is filtered after cooling and washed with toluene to obtain toluene extract. The toluene extract is further washed with hydrochloric acid and water. Toluene is removed under vaccum to obtain a paste or slurry. The slurry is vaccum dried to obtain tetrahydrocurcuminoids. However, the method involves multiple steps of filtration, which increases the cost of the process and also reduces the purity of the final product. In addition, toluene is toxic in nature.
The PCT application numbered PCT/IN2005/000337 titled “Process for producing enriched fractions of tetrahydroxycurcumin and tetrahydrotetrahydroxy-curcumin from the extracts of Curcuma longa” describes a process for producing an enriched fraction of tetrahydoxycurcumin containing tetrahydroxycurcumin, demethylcurcumin, demethylmonodemethoxycurcumin, bisdemethoxycurcumin and colorless tetrahydroderivatives. The process consists of demethylation of natural curcumins. The enriched fraction of tetrahydroxycurcumin is subjected to hydrogenation to get colorless tetrahydrotetrahydroxycurcumin enriched fraction. The enriched fractions of tetrahydroxycurcumin and colorless tetrahydrotetrahydroxycurcumin exhibit potent antioxidative action and reduce inflammation. However, the process may not result in purified form of tetrahydoxycurcumin.
Curcumin processed using the conventional methods is associated with low bioavailability and less heat stability. Hence, there is a need for an improved process for synthesis of white curcumin, which exhibits higher solubility and bioavailability.